Several novel families of amorphous molecular materials with high glass-transition temperatures (Tg) that function as charge-transport or emitting materials for organic LEDs have been deigned and synthesized. Double-layer and multilayer devices using these novel amorphous molecular materials were fabricated and their performance investigated. The use of the novel amorphous molecular materials with high Tgs enabled the fabrication of thermally stable organic LEDs; one of the devices was found to operate even at 170 degrees C. The multilayer device consisting of double hole-transport layers and an emitting layer was found to enhance significantly the durability of the device. Exciplex formation at the organic/organic solid interface in organic LEDs has also been investigated.